Thermostat



Oct. 28. 1924. 1,513,517

G. H. PEIFER THERMOSTAT Filed Nov. 25 1921 I INVENTOH Gar aiFen,

A TTORIVEYS Patented Oct. 28, 1924.

' UNITED STATES 1,513,517 PATENT OFFICE.

GUY'HARRISON PEIFER, OF HAZLETON, PENNSYLVANIA, ASSIGNOR T ANTHRACITE MOTOR SALES 00., OF HAZLETON, PENNSYLVANIA.

THERMO'STAT.

Application filed November 25, 1921. Seriafl No. 517.581.

To all whom it may concern.

Be it known that I, GUY HARRISON PEIFER,

a citizen of the United States, and a resident of Hazleton, in the county of Luzerne and State of Pennsylvania, have invented certain new and useful Improvements in Thermostats, of which the following is a specification.

My invention relates to improvements in thermostats and it consists in the construction, combination and mode of operation herein described and claimed.

One of the objects of the invention is to provide thermostat for the purpose of heat regulation, some of its chief characteristics being simplicity and ruggedness of construction.

Another object of the invention is to provide a closed-circuit thermostat, which functions to operate a fire alarm when the circuit is opened under theinfluence of heat beyond a predetermined temperature.

Another object of the invention is to provide a thermostat With self-cleaning contacts which render the instrument peculiarly adaptable to conditions where it is likely to be subjected to soot and dirt.

Other objects and advantages will appear in the following specification, reference being had to the accompanying drawing, in

which Fig. 1 is a side elevation of the thermostat, the cover being shown in section and the electric circuits in diagram,

Fig. 2 is a plan view of the thermostat,

Fig. 3 is a detail side elevation showing the contact leaves parted under the influence of heat, and

Fig. 4 is a detail view illustrating the selfcleaning action of thecontacts, referred to below.

The construction comprises an iron base 1 on which the upper contact leaf 2 and the thermostatic leaf 3 are mounted by means of insulating blocks 4 and 5 which also electrically separate the two leaves or blades.

The upper contact leaf 2 carries a flat contact 6. The thermostatic blade 3 carries a pointed contact 7. 1 Under ordinary conditions the two contacts engage as shown in Fig. 1, completing a circuit as follows: from the battery B over wire 8 to the binding post 9, through the blade 3 by which the binding post is carried, past the two contacts to the leaf 2, screw 10, bracket 11, blnding post 12,

wire 13, relay 14 and then back to the tive pole of the battery.

The energization of the relay 14 keeps the armature 15 attracted and therefore out of engagementwith the contact 16. Heat causes the thermostatic blade 3 to straighten and even tocurve down as illustrated in ig. 3. When this occurs, the contacts 6 and 7 separate. The circuit embracing the relay 14 becomes deenergized and the armature l5 falls upon the contact 16 closing the following circuit: current flows from the battery over wire 17, contact 16, armature 15,

wire 18 to the gon 19 returning to the battery via wire 20. The alarm is now soundmg.

Regulation for different temperature is obtained by raising or lowering the screw 10. The screw is fixed in its adjustments by the jamb nut 21. Under the adjustment in Fig. 1, there is a slight space between the head of the screw and the upper leaf 2. This leaf is resilient. Heat tends to first straighten the blade 3 and the leaf 2 follows, keeping the contacts 6 and 7 in engagement and consequently the circuit through the relay 14 closed.

Should the heat to which the blade 3 is subjected become excessive, the straightening action will continue. But the end of the leaf 2 will soon reach the head of the screw 10, resulting in the departure of the contact'Zfrom the contact 6 and the opening of the electric circuit 8 with the result described above. A pad 22 of insulation beneath the end of the blade 3. prevents the closure of the circuit 8 should the blade curve down far enough to reach the base.

The operation is readily understood from the description above, but attention is directed to Fig. 4 wherein the self cleaning action of the contacts 6 and 7 is illustrated although the showing is somewhat exaggerated. Since the blades 2 and 3 are separated at their places of mounting 4 and 5, it is evident that thecontacts 6 and 7 must describe slightly difi'erent arcs when relative movement of the blades occurs.

This results in a longitudinal rubbing of one contact on the other as is well illustrated by the full and dotted line positions in Fig. 4. This relative movement or rubbing scrapes a track or in other words provides a perpetually clean place through which the electrical circuit is completed. This feature negaalone is of great importance because the thermostat is often mounted in factories, boiler rooms and like places wherecontinually flying dirt has a tendency to soon blacken and cover all exposed surfaces.

The provision of a cover 23 offers protection from mechanical injury to the instrument. This cover has perforations 24 which provide ventilation.

It is to be observed that there is no re-i striction of the movement of the thermostatic blade 3, which in practice means that this member will not become fatigued and therefore will not lose its power to function.

I. claim 1. A thermostat, comprising va metallic base with an upstanding bracket and a right angled portion, a thermostatic blade having an insulating mounting on the base, another blade having an insulating mounting on the other and extending beyond the free end thereof and under said right angled portion, a screw traversing said portion, passing through an aperture in the aforesaid free end and having a limiting head thereunder, means for fixing adjustments of the screw, a flat contact carried by one blade, a pointed contact carried by the other, and an insulating pad on the base under the thermostatic blade.

2. A thermostat having a base, a pair of common insulating blocks thereon, a contact .leaf fastened on top of the upper block and having an aperture at the opposite end, a thermostatic blade fastened between the blocks and extending short of the end of said leaf, a bracket on the base, means adjustable in said bracket passing through said aperture and having stop means therebeneath, and coacting contacts carried by the leaf and blade in confronting positions, one being flat and the other pointed to scrape the flat contact upon relative movement of the leaf and blade.

GUY HARRISON PEIFER. 

